1. Field of the Invention
The present invention relates to electrosurgical generators and, more particularly, to an improved electrosurgical generator system which enables the power output of the electrosurgical generator of the system to be remotely adjusted by the operator.
2. The Prior Art
A common electrosurgical generator unit provides for adjusting or changing the power output of the generator by the surgeon or other operator using controls at the main controller, i.e., at the control keypad or control panel of the generator, and for controlling at least two different high frequency current outputs for the purpose of cutting or coagulation using switches on the handpiece with which surgery is performed. In this system, the main controller of the unit is outside of the sterile field and is also used to set the particular mode (cutting or coagulation) while the handpiece switches simply activate or interrupt the high frequency current outputs. In other systems, mode selection but not power adjustment can be made at the handpiece. In either event, the need to adjust the power output at the main controller is a disadvantage in that while the surgeon can provide off-on control and, in some units, can control the mode by actuating cut or coagulation switches at the handpiece in the sterile field, the surgeon cannot adjust power in the sterile field and must rely on an assistant to do this.
One approach to the problem is to provide additional switches at the handpiece to enable changing of both the output mode and the power setting from the sterile field. An example of this approach is discussed in U.S. Pat. No. 4,632,109 to Paterson and 4,827,927 to Newton. While this approach enables the level of power delivered by the generator to be changed without having to return to the control panel of the generator (which, as stated, is outside the sterile field), the approach suffers several important disadvantages, including a lack of interchangeability with more conventional units and problems with design due to considerations of controllability and limited installation space.
A further approach to this problem is disclosed in U.S. Pat. No. 5,234,427 to Ohtomo et al. In this patent the handpiece includes cutting and coagulation mode switches and the operator can perform a mode change (e.g., from normal coagulation to spray coagulation) within the sterile field by depression of these two switches simultaneously. In some embodiments, the two switches are simultaneously closed to provide a mode change and a "set-input means" is used to enable the surgeon to cycle through, in a predetermined order, a plurality of different modes. When a particular mode is selected, a "set-process means" instructs the system to change a particular "operating condition" associated with that mode such as the output power of the coagulation mode. In this example, the cutting mode switch can then be used as a level increasing key for increasing the coagulation output power and the coagulation mode switch can be used as a level decreasing switch for decreasing the coagulation output power. Although the electrosurgical unit disclosed in the Ohtomo et al. patent decreases the number of keys that must be provided on the handpiece, the unit suffers disadvantages with respect to the switch manipulations necessary (including, in particular, the need for simultaneous actuation of the coagulation and cutting switches) and the relative complexity of "set-input means" and of the interplay between this "means" and the switch manipulations.